the_white

refractory cement

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ok so I bought 2 4 feet sonotube, one is 8-1/4" inside diameter the other is 10-1/4" I.D. I was thinking 10" and 12" but I tough maybe it would cost to much gas for nothing. I didn't choose the length yet but I'm thinking maybe 18" with what you guys wrote. I didn't count the in.cu ill have inside yet but I will and I will adjust so I can have max 2 burners.

the_white :D

P.S It's Friday now, just finished work and I have to wait until Monday to do the road trip to go buy the stuff I need to build my first forge..... I'm already going nuts, I just wish they were open on weekends.

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Those will give you a nice size forge.

It's the OD of the inside tube that determines the ID of the forge. Confusing I know but once you put them together it'll become obvious. The OD of your smaller tube is probably around 8 1/2" which will give you about a 3/4" thick hard liner wall.

Frosty

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Yeah you are right. I didn't think about it to much when I gave my measurement. It's even better. Just bought 2 7'' stove pipe. I will put them together like you said and I will get 14'' that will be just good when I will add my Kaowool like insulation.

the_white :D

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I was thinking doing a 18'' long forge with 8.5 ID forge. It gives me a 1021.41cu/in inside if I'm not mistaking. I wanted to have a longer forge to be able to heat variable length of stock. But if I do so I need to put 3 burners in if I use 3/4'' burner like you said. Would it work at 2 burners at a bigger size of pipe? Or am I better to build a 12'' forge wich gives 680cu/in.

the_white :D

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seems complicated to me whats wrong with fire brick? also martin did you give up on the whisper mama? i believe its cheaper and easier to buy a propane forge on ebay i got a three burner with guages foor around three hundred delivered had it four years and it still works good still waiting for your call b ut maybe ill call you today

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For that ID and 18 inches long you may need to put 4 burners in if you want welding temp. You are at the upper design limit of these burners. You can always throttle down or turn off extra burners, but if you don't have enough, you will never have enough.

Phil

PS This is why I changed the geometry of my design to an oval. I do not know if it is ideal either. I ordered insulation from Anvilfire today too. Gotta wait till next month to order the rest from Zoeller.
Phil

Edited by pkrankow

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Think about the ratio I recommend for consistent welding heat. one each 3/4" burner for every 250-300 cu/in.

If you use 3/4" burners you'll need three minimum and you'll be in the 300 - 350 per burner and you'll have to get them working at optimum output.

However, a 1" burner has just a bit over twice what a 3/4" burner does, easy consistent welding heat in 700 cu/in. A pair of 1" burners will do the trick.

HOWEVER, just having two larger burners will reduce the consistency of heat in your forge, it'll be less even.

I'd use four 3/4" burners on individual valves and make a movable back wall to reduce the forge's length when I didn't need a long forge.

Frosty

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